diff --git a/bamboo.cabal b/bamboo.cabal
--- a/bamboo.cabal
+++ b/bamboo.cabal
@@ -1,5 +1,5 @@
 Name:                 bamboo
-Version:              2009.5.13
+Version:              2009.5.18
 Build-type:           Simple
 Synopsis:             A simple blog middleware on hack
 Description:          A simple blog middleware on hack
@@ -15,7 +15,7 @@
 
 library
   ghc-options: -Wall -fno-warn-missing-signatures -fno-warn-name-shadowing -fno-warn-orphans -fno-warn-type-defaults
-  build-depends: base, cgi, network, haskell98, old-locale, old-time, time, unix, bytestring, base64-string, zlib, directory, filepath, containers, process,parsedate >= 3000.0.0, rss >= 3000.0.1, xhtml, utf8-string >= 0.3.3, pandoc, parsec >= 2, gravatar >= 0.3, data-default >= 0.2,  mps >= 2009.5.13, hcheat >= 2009.5.13, hack >= 2009.4.52, hack-contrib >= 2009.5.13
+  build-depends: base, cgi, network, haskell98, old-locale, old-time, time, unix, bytestring, base64-string, zlib, directory, filepath, containers, process,parsedate >= 3000.0.0, rss >= 3000.0.1, xhtml, utf8-string >= 0.3.3, pandoc, parsec >= 2, gravatar >= 0.3, data-default >= 0.2,  mps >= 2009.5.13, hcheat >= 2009.5.13, hack >= 2009.4.52, hack-contrib >= 2009.5.13, tokyocabinet-haskell >= 0.0.5
   hs-source-dirs: src/
   exposed-modules:  
                     Bamboo
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,12 @@
+2009.5.18
+---------
+
+### Feature
+
+* use tokyocabinet for caching
+* put `use_cache = y` in `site.txt` to enable
+* cache db will be in `db/cache`
+
 2009.5.13
 ---------
 
diff --git a/src/Bamboo/Config/Global.hs b/src/Bamboo/Config/Global.hs
--- a/src/Bamboo/Config/Global.hs
+++ b/src/Bamboo/Config/Global.hs
@@ -29,6 +29,8 @@
 static_id      = "static"
 topic_id       = "forum/post"
 thumb_id       = "thumb"
+stat_id        = "stat"
+cache_id       = "cache"
 
 db_uri         = db_id
 flat_uri       = db_uri / flat_id
@@ -45,6 +47,8 @@
 
 album_uri      = image_uri / album_id
 topic_uri      = flat_uri / topic_id
+stat_uri       = flat_uri / stat_id
+cache_uri      = flat_uri / cache_id
 
 data ConfigData = 
     BlogTitle
@@ -72,6 +76,7 @@
   | SummaryForRss
   | PicturePrefix
   | NumberOfLatestPosts
+  | UseCache
   deriving (Show)
   
 -- unsafe, must restart server after changing config file, sorry about that ...
@@ -112,7 +117,7 @@
 
 -- extensions
 analytics_account_id = for AnalyticsAccountId
-extensions           = for_list' Extensions "search, comment, analytics" .read_data_list :: [Extension]
+extensions           = for_list' Extensions "search, comment, analytics, counter" .read_data_list :: [Extension]
 
 -- theme
 default_theme   = def
@@ -144,3 +149,8 @@
 -- latest
 number_of_latest_posts = for_int' NumberOfLatestPosts "15"
 
+-- count
+count_meta = "count.meta"
+
+-- cache
+use_cache = for UseCache .parse_boolean
diff --git a/src/Bamboo/Controller/Application.hs b/src/Bamboo/Controller/Application.hs
--- a/src/Bamboo/Controller/Application.hs
+++ b/src/Bamboo/Controller/Application.hs
@@ -18,6 +18,7 @@
 import qualified Bamboo.Type.State as S
 import qualified Bamboo.Config.Global as G
 import qualified Bamboo.Type.Pager as Pager
+import Bamboo.Type.Cache
 import Bamboo.Type.Extension
 import Hack
 import Hack.Contrib.Response (redirect)
@@ -27,6 +28,7 @@
 import qualified Bamboo.Model.Static as Static
 import qualified Bamboo.Model.Tag as Tag
 import qualified Bamboo.Model.Comment as Comment
+import qualified Bamboo.Model.Counter as Counter
 
 -- view
 import qualified Bamboo.View.Control.Post as PostV
@@ -73,14 +75,24 @@
   let state = s { S.uid = G.post_id, S.tags = tags, S.pager = p, S.nav_location = nav }
   
   -- output_html "hi"
-  posts.mapM (init_post tags) ^ PostV.list state >>= output_html
+  posts.for_current_page p .mapM (init_post tags) 
+    >>= cache g (f state)
+    >>= output_plain_html
+  where
+    g = Post.etag_post_list
+    f state = PostV.list state > show > return
 
 index_feed _ = do
   posts <- list
-  posts.RSSV.rss "" "" .output_html
+  posts.take G.number_of_latest_posts .cache g f
+    >>= output_plain_html
+  where
+    g = Post.etag_post_list
+    f xs = xs.RSSV.rss "" "" .show.return
 
 blog env = do
   let id = env .uri .Post.uri_to_id
+  if has_extension Counter then Counter.hit id else return ()
   blog <- get id
   comments <- list_for id
   tags <- tag_list
@@ -88,7 +100,12 @@
   test_data <- S.mk_human_test
   s <- default_state
   let state = s { S.uid = id, S.tags = tags, S.resource_title = blog.resource_title, S.human_test_data = test_data }
-  blog.(init_post tags) ^ PostV.view state comments >>= output_html
+  blog.init_post tags 
+    >>= cache g (f state comments)
+    >>= output_plain_html
+  where
+    g = Post.etag_post
+    f state comments x = x.return ^ PostV.view state comments ^ show
 
 static env = do
   let id = env.uri
@@ -112,8 +129,13 @@
       let p = posts.paginate env
       s <- default_state
       let state = s { S.uid = id, S.tags = tags, S.pager = p, S.resource_title = tag_name.Tag.resource_title_from_name }
-      posts.TagV.view state.output_html
-      
+      posts.for_current_page p .return
+        >>= cache g (f state)
+        >>= output_plain_html
+      where
+        g = Post.etag_post_list
+        f state xs = xs.TagV.view state.show.return
+        
 tag_feed env = do
   let id = env .uri .split "/" .init .join "/"
   tags <- tag_list
@@ -122,7 +144,10 @@
     Nothing -> not_found
     Just post_set -> do
       posts <- post_set.to_list.rsort.mapM get ^ map (Tag.fill_tag tags)
-      posts.RSSV.rss G.tag_id tag_name .output_html
+      posts.take (G.number_of_latest_posts). cache g f >>= output_plain_html
+      where
+        g = Post.etag_post_list
+        f xs = xs.RSSV.rss G.tag_id tag_name.show.return
                 
 search env = do
   let s = env.param_with_default "s" ""
diff --git a/src/Bamboo/Helper/Env.hs b/src/Bamboo/Helper/Env.hs
--- a/src/Bamboo/Helper/Env.hs
+++ b/src/Bamboo/Helper/Env.hs
@@ -21,6 +21,7 @@
   , module System.Directory
   , module Data.Foldable
   , module Data.Default
+  , module Hack.Contrib.Utils
 ) where
 
 import Bamboo.Helper.PreludeEnv hiding (FilePath)
@@ -40,4 +41,4 @@
 import System.Directory
 import Data.Foldable (find)
 import Data.Default
-
+import Hack.Contrib.Utils (httpdate)
diff --git a/src/Bamboo/Helper/Helper.hs b/src/Bamboo/Helper/Helper.hs
--- a/src/Bamboo/Helper/Helper.hs
+++ b/src/Bamboo/Helper/Helper.hs
@@ -22,6 +22,7 @@
 import qualified Prelude as P
 import Data.Default
 import System.Directory
+import System.IO as IO
 import Hack
 import qualified Hack.Contrib.Request as Request
 import Hack.Contrib.Response
@@ -105,13 +106,15 @@
 div_class_id x y = thediv ! [theclass x, id y]
 
 xml_header = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
-output_html x = 
+output_html = show > output_plain_html
+
+output_plain_html x = 
   def 
     .set_status 200
-    .set_body (x.show.unescape_unicode_xml.u2b)
+    .set_body (x.unescape_unicode_xml.u2b)
     .set_content_type _TextHtmlUTF8
     .return
-
+    
 spaced_url = gsub "/" " / "
 
 empty_html = toHtml ""
@@ -127,6 +130,8 @@
 ifM p t f  = p >>= (\p' -> if p' then t else f)
 parse_boolean = belongs_to ["true", "1", "y", "yes", "yeah"]
 mkdir = u2b > createDirectory
+take_directory = u2b > takeDirectory > b2u
+with_file s m f = IO.withFile (s.u2b) m f
 
 -- class
 class DataRenderer a where
@@ -175,5 +180,4 @@
 
 class FlatRead a where
   flat_read :: String -> IO a
-
 
diff --git a/src/Bamboo/Helper/StateHelper.hs b/src/Bamboo/Helper/StateHelper.hs
--- a/src/Bamboo/Helper/StateHelper.hs
+++ b/src/Bamboo/Helper/StateHelper.hs
@@ -5,7 +5,7 @@
 
 module Bamboo.Helper.StateHelper where
 
-import Bamboo.Helper.Env
+import Bamboo.Helper.Env hiding (path)
 import qualified Bamboo.Config.Global as G
 
 -- G.root = /blog
@@ -48,3 +48,10 @@
 
 -- model
 path id = G.flat_uri / id
+id_to_path = path
+
+etag_data id = do
+  let path = id.id_to_path
+  mtime <- path.file_mtime ^ httpdate
+  size <- path.file_size ^ show
+  return $ [id, mtime, size] .join ","
diff --git a/src/Bamboo/Model/Helper.hs b/src/Bamboo/Model/Helper.hs
--- a/src/Bamboo/Model/Helper.hs
+++ b/src/Bamboo/Model/Helper.hs
@@ -3,13 +3,15 @@
 module Bamboo.Model.Helper where
 
 import Bamboo.Helper.Env
+import Bamboo.Helper.StateHelper
 import qualified Bamboo.Config.Global as G
 import Bamboo.Type.Reader
 import Bamboo.Type.Plugin (apply_plugin)
 
-get_body id   = (G.flat_uri / id) .read_file >>= apply_plugin_for_resource id
+get_body id   = id.id_to_path .read_file >>= apply_plugin_for_resource id
 get_reader id = id.take_extension.guess_reader.fromMaybe G.default_reader
 
 apply_plugin_for_resource id
   | id.id_to_type.belongs_to [G.post_id, G.static_id] = apply_plugin
   | otherwise = return
+  
diff --git a/src/Bamboo/Model/Post.hs b/src/Bamboo/Model/Post.hs
--- a/src/Bamboo/Model/Post.hs
+++ b/src/Bamboo/Model/Post.hs
@@ -14,6 +14,9 @@
 import Bamboo.Helper.StateHelper hiding (uri)
 import Bamboo.Helper.Helper (date)
 import Bamboo.Model.Helper
+import Bamboo.Type.Extension
+import Bamboo.Model.Counter
+import qualified Bamboo.Type.Cache as Cache
 
 
 data Post = Post 
@@ -23,6 +26,8 @@
   , tags :: [String]
   , comment_size :: Int
   , reader :: Reader
+  , count :: Int
+  , cache_output :: String
   }
   deriving (Show, Eq)
 
@@ -40,11 +45,11 @@
   uri = uid > id_to_uri
 
 instance Default Post where
-  def = Post def def def def def def
+  def = Post def def def def def def def def
 
 instance FlatRead Post where
   flat_read x = do
-    t <- get_body x
+    t <- x.Cache.cache etag_data get_body
     def {body = t, uid = x} .return
 
 -- CRUD
@@ -55,15 +60,29 @@
         title = get_title id
       , reader = get_reader id
       }
-      .return
+      .fill_stat
 
 instance Listable Post where
   list = list_ids >>= mapM get
   cheat_list = fast_list
 
+etag_post x' = do
+  x <- x'.fill_stat
+  let id = x.uid
+  let path = id.id_to_path
+  mtime <- path.file_mtime ^ httpdate
+  size <- path.file_size ^ show
+  return $ [id, mtime, size, x.comment_size.show, x.count.show] .join ","
+
+etag_post_list xs = xs.mapM etag_post ^ join ","
+  
 list_ids = ls G.post_uri ^ rsort ^ map (G.post_id /)
 fast_list = list_ids ^ map (\x -> def {uid = x, title = x.get_title})
 
+fill_stat x | has_extension Counter = do
+    c <- x.uid.read_stat
+    x {count = c} .return
+fill_stat x = return x
 
 get_title id  = id.words.tail.unwords.drop_known_extension
 get_date id   = id.words.first.split "/".last.default_parse_date
diff --git a/src/Bamboo/Model/Tag.hs b/src/Bamboo/Model/Tag.hs
--- a/src/Bamboo/Model/Tag.hs
+++ b/src/Bamboo/Model/Tag.hs
@@ -5,8 +5,10 @@
 
 -- env
 import Bamboo.Helper.Env hiding (name)
+import Bamboo.Helper.StateHelper
 import qualified Data.Set as S
 import qualified Bamboo.Config.Global as G
+import Bamboo.Type.Cache
 
 
 data Tag = Tag 
@@ -21,15 +23,16 @@
 
 -- CRUD
 instance Gettable Tag where
-  get id           = get_resources id ^ Tag id (get_name id)
+  get id           = get_resources_set id ^ Tag id (get_name id)
 
 instance Listable Tag where
   list             = ls G.tag_uri ^ map (G.tag_id /) >>= mapM get
 
 
 get_name id      = id.split "/" .tail.join'
-get_resources id = (G.flat_uri / id) .read_file
-  ^ filter_comment ^ lines ^ map (G.post_id / ) ^ to_set
+get_resources id = id.id_to_path.read_file ^ filter_comment
+
+get_resources_set id = id.cache etag_data get_resources ^ lines ^ map (G.post_id / ) ^ to_set
 
 resource_title_from_name x = ("tag" / x) .spaced_url
 tag_map' xs       = xs . map (name &&& resources) . to_h
diff --git a/src/Bamboo/Type/Extension.hs b/src/Bamboo/Type/Extension.hs
--- a/src/Bamboo/Type/Extension.hs
+++ b/src/Bamboo/Type/Extension.hs
@@ -7,6 +7,7 @@
     Comment
   | Search
   | Analytics
+  | Counter
   deriving (Show, Read, Eq)
 
 
diff --git a/src/Bamboo/View/Atom/Post.hs b/src/Bamboo/View/Atom/Post.hs
--- a/src/Bamboo/View/Atom/Post.hs
+++ b/src/Bamboo/View/Atom/Post.hs
@@ -26,7 +26,7 @@
 show_content Full    x = x.markup
 
 -- post could also be a summary
-render_summary x = if x.is True then entry Summary else render_data
+render_summary flag = if flag then entry Summary else render_data
 
 title_link x              = h2 << hotlink (x.uri) << x.title
 post_date x               = toHtml $ x.date.format_time "%b %e, %Y"
diff --git a/src/Bamboo/View/Control/Post.hs b/src/Bamboo/View/Control/Post.hs
--- a/src/Bamboo/View/Control/Post.hs
+++ b/src/Bamboo/View/Control/Post.hs
@@ -26,6 +26,6 @@
   where comment_view = only_for Comment $ CommentV.list xs +++ CommentV.create state (x.uid.Comment.from_post_id)
 
 -- list view
-list state = for_current_page p > map render > p_eval' > (+++ nav p G.root) > page state where 
+list state = map render > p_eval' > (+++ nav p G.root) > page state where 
   p = state.State.pager
   render = render_summary G.summary_for_root
diff --git a/src/Bamboo/View/Control/Tag.hs b/src/Bamboo/View/Control/Tag.hs
--- a/src/Bamboo/View/Control/Tag.hs
+++ b/src/Bamboo/View/Control/Tag.hs
@@ -12,7 +12,7 @@
 import Bamboo.View.Widget.Template
 
 
-view state = for_current_page p > map render > p_eval' > (+++ nav p ( G.root / tag_id)) >>> page state where
+view state = map render > p_eval' > (+++ nav p ( G.root / tag_id)) >>> page state where
   p = state.State.pager
   tag_id = state.State.uid
   render = render_summary G.summary_for_tag
diff --git a/src/Bamboo/View/Widget/RSS.hs b/src/Bamboo/View/Widget/RSS.hs
--- a/src/Bamboo/View/Widget/RSS.hs
+++ b/src/Bamboo/View/Widget/RSS.hs
@@ -30,7 +30,7 @@
 item_uri x = def { uriScheme = "http://", uriPath = host_link (x.uri) }
 rss_uri x  = def { uriScheme = "http://", uriPath = host_link x }
 
-rss categary s xs = RSS title  (rss_uri link) title channel_rss_template (xs.take 20 .map item_rss_template)
+rss categary s xs = RSS title  (rss_uri link) title channel_rss_template (xs.map item_rss_template)
   .rssToXML.showXML
   where
     link = categary / s